Patients may stop having menstrual periods or have months with no periods followed by bouts of heavy bleeding.

Many women with PCOS also develop problems with insulin, causing a condition known as insulin resistance. By age 40, as many as 40 percent of PCOS patients have diabetes.

"The condition is really misnamed, because it's a metabolic disorder, a hormone disorder," says Dr. Jennifer Hayes, a St. Anthony's Hospital gynecologist and the physician who treated English for PCOS. The condition got its name from the small benign cysts that form on a patient's ovaries, but, Hayes says, it's the mixed-up signals sent to the brain and the resulting hormonal imbalance that cause problems.

Because the body has trouble using insulin, most women with PCOS have a weight problem.

"PCOS puts the body into a weight-gaining mode," Hayes says. "Their brain is telling them to eat sugar, so they crave carbs. It makes for crazy mood swings, accelerated weight gain and difficult weight loss."

PCOS affects up to one in 15 American teens and women, but can be so mild that patients don't seek treatment.

Treatment depends on a patient's goals, but most doctors immediately put patients on an exercise program and a low-carbohydrate, heart-healthy diet to promote weight loss. They may also prescribe birth control medication to bring menstrual cycles under control and to reduce acne, facial hair growth and hair loss.

But, if infertility is the chief complaint, as it was for Carrie English, patients may be offered the diabetes medication metformin, which helps control blood sugar and androgen hormone levels, and can also help trigger ovulation. If that alone doesn't work, other fertility medication may be added.

English was prepared to wait the year or two that her doctor said it could take to normalize her hormones and achieve pregnancy. But, within three months of starting metformin, she was delighted to learn she was pregnant.

"I took three home pregnancy tests, because I thought it was wrong," she recalls.

There's no cure for PCOS, so patients must always keep symptoms in check. But English says her infertility issues are over.

After the birth of her second child, son Aidan in 2006, she says, "We're done."